Adhesion improvement for low k dielectrics

ABSTRACT

Methods are provided for processing a substrate for depositing an adhesion layer having a low dielectric constant between two low k dielectric layers. In one aspect, the invention provides a method for processing a substrate including introducing an organosilicon compound and an oxidizing gas at a first ratio of organosilicon compound to oxidizing gas into the processing chamber, generating a plasma of the oxidizing gas and the organosilicon compound to form an initiation layer on a barrier layer comprising at least silicon and carbon, introducing the organosilicon compound and the oxidizing gas at a second ratio of organosilicon compound to oxidizing gas greater than the first ratio into the processing chamber, and depositing a first dielectric layer adjacent the dielectric initiation layer.

BACKGROUND OF THE DISCLOSURE

1 Field of the Invention

The invention relates to the fabrication of integrated circuits and to aprocess for depositing dielectric layers on a substrate and thestructures formed by the dielectric layer.

2. Description of the Related Art

One of the primary steps in the fabrication of modern semiconductordevices is the formation of metal and dielectric layers on a substrateby chemical reaction of gases. Such deposition processes are referred toas chemical vapor deposition or CVD. Conventional thermal CVD processessupply reactive gases to the substrate surface where heat-inducedchemical reactions take place to produce a desired layer.

Semiconductor device geometries have dramatically decreased in sizesince such devices were first introduced several decades ago. Sincethen, integrated circuits have generally followed the two year/half-sizerule (often called Moore's Law), which means that the number of devicesthat will fit on a chip doubles every two years. Today's fabricationplants are routinely producing devices having 0.35 μm and even 0.18 μmfeature sizes, and tomorrow's plants soon will be producing deviceshaving even smaller geometries.

To further reduce the size of devices on integrated circuits, it hasbecome necessary to use conductive materials having low resistivity andto use insulators having low dielectric constants (dielectricconstant<4.0) to also reduce the capacitive coupling between adjacentmetal lines. One such low k dielectric material is spin-on glass, suchas un-doped silicon glass (USG) or fluorine-doped silicon glass (FSG),which can be deposited as a gap fill layer in a semiconductormanufacturing process. Another low k dielectric material is siliconoxycarbide that can used as a dielectric layer in fabricating damascenefeatures.

One conductive material gaining acceptance is copper and its alloys,which have become the materials of choice for sub-quarter-microninterconnect technology because copper has a lower resistivity thanaluminum, (1.7 μΩ-cm compared to 3.1 μΩ-cm for aluminum), a highercurrent and higher carrying capacity. These characteristics areimportant for supporting the higher current densities experienced athigh levels of integration and increased device speed. Further, copperhas good thermal conductivity and is available in a very pure state.

One difficulty in using copper in semiconductor devices is that copperis difficult to etch to achieve a precise pattern; Etching with copperusing traditional deposition/etch processes for forming interconnectshas been less than satisfactory. Therefore, new methods of manufacturinginterconnects having copper containing materials and low k dielectricmaterials are being developed.

One method for forming vertical and horizontal interconnects is by adamascene or dual damascene method. In the damascene method, one or moredielectric materials, such as the low k dielectric materials, aredeposited and pattern etched to form the vertical interconnects, i.e.vias, and horizontal interconnects, i.e., lines. Conductive materials,such as copper containing materials, and other materials, such asbarrier layer materials used to prevent diffusion of copper containingmaterials into the surrounding low k dielectric, are then inlaid intothe etched pattern. Any excess copper containing materials and excessbarrier layer material external to the etched pattern, such as on thefield of the substrate, are then removed.

However, when silicon oxycarbide layers and silicon carbide layers areused as the low k material in damascene formation, less thansatisfactory interlayer adhesion has been observed during processing.Some techniques for processing substrates may apply forces that canincrease layering defects, such as layer delamination. For example,excess copper containing materials may be removed by mechanical abrasionbetween a substrate and a polishing pad in a chemical mechanicalpolishing process, and the force between the substrate and the polishingpad may induce stresses in the deposited low k dielectric materials toresult in layer delamination. In another example, annealing of depositedmaterials may induce high thermal stresses that can also lead todelamination in low k dielectric materials.

Therefore, there remains a need for a process for improving interlayeradhesion between low k dielectric layers.

SUMMARY OF THE INVENTION

Aspects of the invention generally provide a method for depositing anadhesion layer having a low dielectric constant between two low kdielectric layers. In one aspect, the invention provides a method forprocessing a substrate including positioning the substrate in aprocessing chamber, wherein the substrate has a barrier layer comprisingat least silicon and carbon, introducing an organosilicon compound andan oxidizing gas at a first ratio of organosilicon compound to oxidizinggas into the processing chamber, generating a plasma of the oxidizinggas and the organosilicon compound to form an initiation layer on thebarrier layer, introducing the organosilicon compound and the oxidizinggas at a second ratio of organosilicon compound to oxidizing gas greaterthan the first ratio into the processing chamber, and depositing a firstdielectric layer adjacent the dielectric initiation layer, wherein thedielectric layer comprises silicon, oxygen, and carbon and has adielectric constant of about 3 or less.

In another aspect of the invention, a method is provided for processinga substrate including positioning the substrate in a processing chamber,wherein the substrate has a barrier layer comprising silicon, nitrogen,and carbon, introducing an inert gas into the processing chamber,generating a first plasma from a single-frequency RF power source tomodify a surface of the barrier layer, introducing an organosiliconcompound and an oxidizing gas in a ratio of about 1:1 into theprocessing chamber, generating a second plasma from a dual-frequency RFpower source to form an initiation layer on the barrier layer,introducing the organosilicon compound and the oxidizing gas in a ratioof greater than about 10:1 into the processing chamber, and depositing afirst dielectric layer adjacent the dielectric initiation layer, whereinthe dielectric layer comprises silicon, oxygen, and carbon and has adielectric constant of about 3 or less.

In another aspect of the invention, a method is provided for processinga substrate including positioning the substrate in a processing chamber,wherein the substrate has a barrier layer comprising at least siliconand carbon, introducing an oxidizing gas into the processing chamber,generating a plasma of the oxidizing gas and treating a surface of thebarrier layer, introducing an organosilicon compound at a first flowrate, depositing an initiation layer on the barrier layer from theoxidizing gas and the organosilicon compound, introducing theorganosilicon compound at a second flow rate greater than the first flowrate, depositing a first dielectric layer adjacent the dielectricinitiation layer from the oxidizing gas and the organosilicon compound,wherein the dielectric layer comprises silicon, oxygen, and carbon andhas a dielectric constant of about 3 or less.

In another aspect of the invention, a method is provided for processinga substrate including positioning the substrate in a processing chamber,wherein the substrate has a barrier layer comprising at least siliconand carbon, introducing an oxidizing gas into the processing chamber,generating a plasma of the oxidizing gas and forming an initiation layeron the barrier layer, introducing an organosilicon compound into theprocessing chamber, reacting the organosilicon compound and theoxidizing gas, and depositing a first dielectric layer adjacent theinitiation layer, wherein the dielectric layer comprises silicon,oxygen, and carbon and has a dielectric constant of about 3 or less.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above aspects of the invention areattained and can be understood in detail, a more particular descriptionof the invention, briefly summarized above, may be had by reference tothe embodiments thereof which are illustrated in the appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a cross-sectional view showing a dual damascene structurecomprising the silicon carbide and silicon oxycarbide layers describedherein; and

FIGS. 2A-H are cross-sectional views showing one embodiment of a dualdamascene deposition sequence of the invention.

For a further understanding of aspect of the invention, reference shouldbe made to the ensuing detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Aspects of the invention described herein refer to a method andapparatus for depositing an adhesive dielectric material and/or treatingthe surface between dielectric layers to improve interlayer adhesion ofdielectric layers. Improving interlayer adhesion may comprise forming adielectric initiation layer before depositing a subsequent dielectriclayer. The initiation layer may comprise silicon, carbon, andoptionally, oxygen. Treatments to improve adhesion between thedielectric layers include modifying the surface of a deposited layerprior to subsequent deposition, for example, the application of a plasmatreatment of an inert gas, an oxidizing gas, or both. Treating of thesurface of a silicon, carbon, and optionally, oxygen containing materialis believed to form a more oxide-like surface on the deposited materialto thereby improve interlayer adhesion.

Deposition of a Dual Damascene Structure

A damascene structure that is formed using the deposition processesdescribed herein for a silicon oxycarbide layer disposed on a siliconcarbide layer is shown in FIG. 1. The following structure formingprocess as described in FIGS. 1 and 2A-2H are illustrative and shouldnot be construed or interpreted as limiting the scope of the invention.While the following interlayer adhesion processes are used between asilicon carbide barrier layer 112 and a dielectric layer 110 as well asa low k etch stop layer 114 and an interlayer dielectric layer 118, theinvention contemplates that the interlayer adhesion processes may beused between any suitable dielectric layers in a damascene structure ordielectric stack.

A substrate 100 having metal features 107 formed in a substrate surfacematerial 105 therein is provided to a processing chamber. A firstsilicon carbide barrier layer 112 is generally deposited on thesubstrate surface to eliminate inter-level diffusion between thesubstrate and subsequently deposited material. The first silicon carbidebarrier layer 112 may be nitrogen and/or oxygen doped. Barrier layermaterials may have dielectric constants of up to about 9, such as 4 orless, and preferably between about 2.5 and less than about 4. Siliconcarbide barrier layers may have dielectric constants of about 5 or less,preferably less than about 4. A capping layer of nitrogen free siliconcarbide (not shown) may be deposited in situ on the first siliconcarbide barrier layer 112 by minimizing or eliminating the nitrogensource gas. An initiation layer 113 may be deposited on the firstsilicon carbide barrier layer 112, and a pre-treatment process asdescribed herein may be used prior to depositing the initiation layer113.

The first dielectric layer 110 of the oxidized organosilicon compound isdeposited on initiation layer 113. The first dielectric layer 110 maythen be post-treated with a plasma or e-beam process. Alternatively, asilicon oxide cap layer (not shown) may be deposited in situ on thefirst dielectric layer 110 by increasing the oxygen concentration in thesilicon oxycarbide deposition process described herein to remove carbonfrom the deposited material.

An etch stop (or second barrier layer) 114 of a silicon carbide, whichmay be doped with nitrogen or oxygen, is then deposited on the firstdielectric layer 110. The etch stop 114 may have a nitrogen free siliconcarbide capping layer deposited thereon. The etch stop 114 is thenpattern etched to define the openings of the contacts/vias 116. Aninterlayer adhesion layer or initiation layer 115 as described hereinmay be formed on the layer 114 prior to subsequent processing, such asetching or additional dielectric etching, to improve interlayer adhesionwith subsequently deposited dielectric materials. The improved adhesionlayer may comprise the pre-treatment process and initiation layer asdescribed herein. The interlayer adhesion surface may be formed by thetechniques described herein. A second dielectric layer 118 of anoxidized organosilane or organosiloxane is then deposited over thepatterned etch stop. The second dielectric layer 118 may then be plasmaor e-beam treated and/or have a silicon oxide cap material disposedthereon by the process described herein.

A resist 122, conventionally known in the art, such as photoresistmaterial UV-5, commercially available from Shipley Company Inc., ofMarlborough, Mass., is then deposited and patterned by conventionalmeans known in the art to define the interconnect lines 120. A singleetch process is then performed to define the interconnect down to theetch stop and to etch the unprotected dielectric exposed by thepatterned etch stop to define the contacts/vias.

A preferred dual damascene structure fabricated in accordance with theinvention includes the plasma treatment or e-beam treatment of anexposed silicon oxycarbide layer as shown in FIG. 2E, and the method ofmaking the structure is sequentially depicted schematically in FIGS.2A-2H, which are cross-sectional views of a substrate having the stepsof the invention formed thereon.

As shown in FIG. 2A, a first silicon carbide barrier layer 112 isdeposited on the substrate surface. The silicon carbide material of thefirst silicon carbide barrier layer 112 may be doped with nitrogenand/or oxygen. While not shown, a capping layer of nitrogen free siliconcarbide or silicon oxide may be deposited on the barrier layer 112. Thenitrogen free silicon carbide or silicon oxide may be deposited in situby adjusting the composition of the processing gas.

The initiation layer 113 may be deposited by a plasma treatment of thefirst silicon carbide barrier layer 112 followed by the actualinitiation layer material deposition; both processes may be performedsequentially in situ. Helium (He), argon (Ar), neon (Ne), andcombinations thereof, may be used for the plasma treatment.

An example of the inert gas pre-treatment process comprises providinghelium to a processing chamber at a flow rate of about 1500 sccm,maintaining a chamber pressure of about 5 Torr, maintaining a substratetemperature of about 350° C., positioning a gas distributor at about 450mils from the substrate surface, and generating a plasma by applying aRF power level of about 300 W at a high frequency of about 13.56 MHz fora period of 15 seconds.

An example of a deposition of initiation layer 113 comprises introducingoxygen at a flow rate of 500 sccm into the processing chamber,introducing octamethylcyclotetrasiloxane at a flow rate of about 500milligrams/minute (mgm) (which corresponds to about 39 sccm for OMCTS),introducing helium at a flow rate of about 4800 sccm, maintaining thechamber at a substrate temperature of about 350° C., maintaining achamber pressure of about 5 Torr, positioning a gas distributor at about350 mils from the substrate surface, and applying a RF power of about500 watts at 13.56 Mhz and about 150 watts at 356 KHz.

An initial first dielectric layer 110 of silicon oxycarbide from anoxidized organosilane or organosiloxane by the process described herein,such as trimethylsilane and/or octamethylcyclotetrasiloxane, isdeposited on initiation layer 113 to a thickness of about 5,000 to about15,000 Å, depending on the size of the structure to be fabricated. Thefirst dielectric layer may also comprise other low k dielectric materialsuch as a low polymer material including paralyne or a low k spin-onglass such as un-doped silicon glass (USG) or fluorine-doped siliconglass (FSG). The first dielectric layer may then be treated by a plasmaprocess as described herein.

As shown in FIG. 2B, the low k etch stop 114, which may be nitrogenand/or oxygen doped silicon carbide, is then deposited on the firstdielectric layer to a thickness of about 100 Å to about 1000 Å. Aninterlayer dielectric adhesion layer or surface 115 formed by one of theprocesses described herein, such as a dielectric initiation layer, isthen formed or deposited on the low k etch stop layer 114. The low ketch stop 114 and/or interlayer dielectric adhesion layer or surface 115may be plasma treated as described herein for the silicon carbidematerials or silicon oxycarbide materials. Layer 115 may be deposited asdescribed for initiation layer 113.

The low k etch stop 114 is then pattern etched to define the contact/viaopenings 116 and to expose first dielectric layer 110 in the areas wherethe contacts/vias are to be formed as shown in FIG. 2C. Preferably, thelow k etch stop 114 is pattern etched using conventionalphotolithography and etch processes using fluorine, carbon, and oxygenions. While not shown, a nitrogen-free silicon carbide or silicon oxidecap layer between about 10 Å to about 500 Å may be deposited on the lowk etch stop 114 and/or interlayer dielectric adhesion layer or surface115 prior to depositing further materials.

After low k etch stop 114 has been etched to pattern the contacts/viasand the resist material has been removed, a second dielectric layer 118of silicon oxycarbide from an oxidized organosilane or organosiloxane bythe process described herein, such as trimethylsilane, is deposited to athickness of about 5,000 to about 15,000 Å as shown in FIG. 2D. Thesecond dielectric layer 118 may then be treated by a plasma process asdescribed herein for first dielectric layer 110.

A resist material 122 is then deposited on the second dielectric layer118 (or cap layer) and patterned: preferably using conventionalphotolithography processes to define the interconnect lines 120 as shownin FIG. 2E. The resist material 122 comprises a material conventionallyknown in the art, preferably a high activation energy resist material,such as UV-5, commercially available from Shipley Company Inc., ofMarlborough, Mass. The interconnects and contacts/vias are then etchedusing reactive ion etching or other anisotropic etching techniques todefine the metallization structure (i.e., the interconnect andcontact/via) as shown in FIG. 2F. Any resist material or other materialused to pattern the etch stop 114 or the second dielectric layer 118 isremoved using an oxygen strip or other suitable process.

The metallization structure is then formed with a conductive materialsuch as aluminum, copper, tungsten or combinations thereof. Presently,the trend is to use copper to form the smaller features due to the lowresistivity of copper (1.7 mΩ-cm compared to 3.1 mΩ-cm for aluminum).Preferably, as shown in FIG. 2G, a suitable metal barrier layer 124,such as tantalum nitride, is first deposited conformally in themetallization pattern to prevent copper migration into the surroundingsilicon and/or dielectric material. Thereafter, copper 126 is depositedusing either chemical vapor deposition, physical vapor deposition,electroplating, or combinations thereof to form the conductivestructure. Once the structure has been filled with copper or otherconductive metal, the surface is planarized using chemical mechanicalpolishing, as shown in FIG. 2H.

Initiation Layer Deposition

In one aspect, interlayer adhesion may be improved by depositing aninitiation layer prior to depositing the silicon oxycarbide layer.Optionally, a pre-treatment process of the underlying dielectric layer,such as silicon carbide or doped silicon carbide, may be performed priorto deposition of the initiation layer. The application of the RF powerto generate a plasma may not end during gas transition betweenpre-treatment steps and/or deposition steps.

The following deposition processes are described with use of the 300 mmProducer™ dual deposition station processing chamber, and should beinterpreted accordingly, for example, flow rates are total flow ratesand should be divided by two to describe the process flow rates at eachdeposition station in the chamber. Additionally, it should be noted thatthe respective parameters may be modified to perform the plasmaprocesses in various chambers and for different substrate sizes, such asfor 200 mm substrates.

The deposition processes described herein may be performed in onecontinuous plasma process, or comprise two or more generated plasma, forexample, one for each layer deposition step. The pre-treatment anddeposition processes described herein may also be performed in onecontinuous plasma process, or comprise two or more generated plasma, forexample, one generated plasma for the pretreatment process and one ormore generated plasma for the layer deposition steps; or one plasma forthe pre-treatment process and initiation layer deposition step and asecond generated plasma for the dielectric deposition step.

The pre-treatment process comprises a plasma treatment of the underlyingdielectric using an inert gas, an oxidizing gas, or both. The plasmatreatment is believed to form a surface of the underlying dielectricmaterial more similar to the subsequently deposited material. Forexample, it is believed the oxygen plasma creates a more oxide likesurface. The plasma treatment may be performed in the same chamber usedto deposit the silicon oxycarbide material.

One embodiment of the plasma treatment comprises providing an inert gas,including helium, argon, neon, xenon, krypton, or combinations thereof,to a processing chamber at a flow rate between about 500 sccm and about3000 sccm, maintaining a chamber pressure between about 3 Torr and about12 Torr, maintaining a substrate temperature between about 300° C. andabout 450° C., positioning a gas distributor, or “showerhead” that maybe positioned between about 200 mils and about 1000 mils, for examplebetween 300 mils and 500 mils from the substrate surface, and generatinga plasma by applying a power density ranging between about 0.03 W/cm²and about 3.2 W/cm², which is a RF power level of between about 10 W andabout 1000 W for a 200 mm substrate, at a high frequency such as between13 MHz and 14 MHz, for example, 13.56 MHz. The plasma treatment may beperformed between about 3 seconds and about 120 seconds, for example,between about 5 seconds and about 40 seconds preferably used.

The plasma may be generated by a dual-frequency RF power source asdescribed herein. Alternatively, all plasma generation may be performedremotely, with the generated radicals introduced into the processingchamber for plasma treatment of a deposited material or deposition of amaterial layer.

An example of the inert gas pre-treatment process comprises providinghelium to a processing chamber at a flow rate of about 1500 sccm,maintaining a chamber pressure of about 5 Torr, maintaining a substratetemperature of about 350° C., positioning a gas distributor at about 450mils from the substrate surface, and generating a plasma by applying aRF power level of about 300 W at a high frequency of about 13.56 MHz fora period of 15 seconds.

The pre-treatment plasma process may utilize an oxidizing gas, such asoxygen, with or without the inert gas described above. The oxidizingpre-treatment process may comprise providing an oxidizing gas, such asoxygen or other oxidizing gas described herein, to a processing chamberat a flow rate between about 100 sccm and about 3000 sccm, maintaining achamber pressure between about 2 Torr and about 12 Torr, maintaining asubstrate temperature between about 250° C. and about 450° C.,positioning a gas distributor, or “showerhead” that may be positionedbetween about 200 mils and about 1000 mils, for example between about300 mils and about 500 mils from the substrate surface, and generating aplasma by applying a power density ranging between about 0.03 W/cm² andabout 3.2 W/cm², which is a RF power level of between about 10 W andabout 1000 W for a 200 mm substrate, at a high frequency such as between13 MHz and 14 MHz, for example, 13.56 MHz. The plasma treatment may beperformed between about 3 seconds and about 120 seconds, with a plasmatreatment between about 5 seconds and about 40 seconds preferably used.

An example of the oxidizing gas pre-treatment process comprisesproviding oxygen to a processing chamber at a flow rate of about 750sccm (about 1500 sccm for a dual station Producer™ plasma chamber),maintaining a chamber pressure of about 5 Torr, maintaining a substratetemperature of about 350° C., positioning a gas distributor at about 450mils from the substrate surface, and generating a plasma by applying aRF power level of about 300 W at a high frequency of about 13.56 MHz fora period of 15 seconds.

An initiation layer may be deposited on the underlying material, such asa silicon carbide layer that may comprise nitrogen or oxygen dopedsilicon carbide, to seed the deposition of subsequent dielectric layer,such as a silicon oxycarbide layer.

The initiation layer may comprise a silicon oxycarbide layer and may bedeposited by an oxidizing gas and an organosilicon material, whichorganosilicon compound may be such compounds as described herein. Theorganosilicon compound and the oxidizing gas may be introduced into theprocessing chamber at a ratio of organosilicon compound (mgm) tooxidizing gas (sccm) of between about 1:2 and about 10:1, such asbetween about 1:2 and about 2:1, for example between about 1:2 and about1:1. The initiation layer may be deposited at processing conditionsapproximately or equivalent to the subsequent dielectric materialdeposition, such as a silicon oxycarbide deposition.

The initiation layer and silicon oxycarbide layer may be depositedsequentially in situ by modifying the processing gas compositions. Forexample, the silicon oxycarbide layer may be deposited by introducingthe organosilicon compound and the oxidizing gas into the processingchamber at a ratio of organosilicon compound (mgm) to oxidizing gas(sccm) of between about 10:1 or greater, such as between about 10:1 andabout 201, for example about 18:1; and in situ processing may occur bychanging the ratios of organosilicon compound and oxidizing gas betweendeposition of the initiation layer and silicon oxycarbide layer. Theoxidizing gas may comprise an oxidizing compound selected from the groupof oxygen, ozone, carbon monoxide, carbon dioxide, nitrous oxide, andcombinations thereof, of which, oxygen is preferred.

The pre-treatment process may also be performed in situ with theinitiation layer deposition and/or silicon oxycarbide layer deposition.All flow ratios between the organosilicon compound and the oxidizing gasfor deposition process are described in units of mgm to sccm unlessotherwise noted.

One embodiment of a deposition of dielectric initiation layer is asfollows. The deposition may be performed by introducing an oxidizingcompound at a flow rate between about 10 sccm and about 2000 sccm intothe processing chamber, introducing an organosilicon precursor at a flowrate between about 100 milligrams/minute (mgm) and about 5000 mgm (whichcorresponds to between about 7 sccm and about 400 sccm foroctamethylcyclotetrasiloxane (OMCTS)), and optionally, supplying a noblegas at a flow rate between about 1 sccm and about 10000 sccm,maintaining the chamber at a substrate temperature between about 0° C.and about 500° C., maintaining a chamber pressure between about 100milliTorr and about 100° Torr, positioning a gas distributor betweenabout 200 mils and about 700 mils from the substrate surface, andapplying a RF power of between about 0.03 watts/cm² and about 1500watts/cm, such as between about 0.03 W/cm² and about 6.4 W/cm, which isa RF power level of between about 10 W and about 2000 W for a 200 mmsubstrate.

The power may be applied from a dual-frequency RF power source a firstRF power with a frequency in a range of about 10 MHz and about 30 MHz ata power in a range of about 200 watts to about 1000 watts and at least asecond RF power with a frequency in a range of between about 100 KHz andabout 500 KHz as well as a power in a range of about 1 watt to about 200watts. The initiation layer may be deposited for a period of timebetween about 1 second and 60 seconds, for example between about 1 andabout 5 seconds, such as 2 seconds.

An example of a deposition of initiation layer comprises introducingoxygen at a flow rate of 500 sccm into the processing chamber,introducing octamethylcyclotetrasiloxane at a flow rate of about 500milligrams/minute (mgm) (which corresponds to about 39 sccm for OMCTS),introducing helium at a flow rate of about 4800 sccm, maintaining thechamber at a substrate temperature of about 350° C., maintaining achamber pressure of about 5 Torr, positioning a gas distributor at about350 mils from the substrate surface, and applying a RF power of about500 watts at 13.56 MHz and about 150 watts at 356 KHz. The process wasperformed between about 1 and about 5 seconds, preferably about 2seconds.

In an alternative embodiment of the initiation layer formation, anoxygen plasma pre-treatment process may be initiated and applied for afirst period of time, and then the organosilicon material may beintroduced for the initiation layer deposition. This allows forcontiguous pre-treatment of the deposited material by an oxidizingplasma and subsequent initiation layer deposition in situ prior todeposition of the subsequent dielectric material, which may also beperformed in situ.

The dielectric material may comprise silicon oxycarbide deposited in oneembodiment by introducing an oxidizing compound, such as oxygen, at aflow rate between about 10 sccm and about 2000 sccm into the processingchamber, introducing an organosilicon precursor at a flow rate betweenabout 100 milligrams/minute (mgm) and about 5000 mgm (which correspondsto between about 7 sccm and about 400 sccm for OMCTS), and optionally,supplying a noble gas at a flow rate between about 1 sccm and about10000 sccm, maintaining the chamber at a substrate temperature betweenabout 0° C. and about 500° C., maintaining a chamber pressure betweenabout 100 milliTorr and about 100 Torr, positioning a gas distributorbetween about 200 mils and about 700 mils from the substrate surface,and applying a RF power of between about 0.03 watts/cm and about 1500watts/cm², such as between about 0.03 W/cm² and about 6.4 W/cm which isa RF power level of between about 10 W and about 2000 W for a 200 mmsubstrate. The power may be applied from a dual-frequency RF powersource a first RF power with a frequency in a range of about 10 MHz andabout 30 MHz at a power in a range of about 200 watts to about 1000watts and at least a second RF power with a frequency in a range ofbetween about 100 KHz and about 500 KHz as well as a power in a range ofabout 1 watt to about 200 watts.

An example of a deposition of a dielectric layer comprises introducingoxygen at a flow rate of 160 sccm into the processing chamber,introducing octamethylcyclotetrasiloxane at a flow rate of about 2900milligrams/minute (mgm) (which corresponds to about 226 sccm for OMCTS),introducing helium at a flow rate of about 1000 sccm, maintaining thechamber at a substrate temperature of about 350° C., maintaining achamber pressure of about 5 Torr, positioning a gas distributor at about450 mils from the substrate surface, and applying a RF power of about500 watts at 13.56 MHz and about 150 watts at 356 KHz. The initiationlayer deposition process and the dielectric layer may be deposited insitu and contiguous by adjusting the precursor flow rates and otherprocessing parameters.

EXAMPLES

The following examples demonstrate various embodiments of the adhesionprocesses described herein as compared to a standard interlayer stack toillustrate the improved interlayer adhesion. The samples were undertakenusing a Producer™ 300 mm processing chambers, which includes asolid-state dual frequency RF matching unit with a two-piece quartzprocess kit, both fabricated and sold by Applied Materials, Inc., SantaClara, Calif.

Test samples were prepared as follows. A stack of dielectric layers weredeposited on a silicon substrate as follows. The substrate comprises asilicon substrate having about 1000 Å of oxide disposed thereon, about250 Å of tantalum disposed on the oxide, about 4500 Å of copper disposedon the tantalum, about 2000 Å of silicon carbonitride disposed on thecopper layer, and about 2000 Å of silicon oxycarbide deposited on thesilicon carbonitride layer. The silicon carbonitride deposition and thesilicon oxycarbide deposition may be one continuous plasma or maycomprise two or more generated plasmas.

The silicon oxycarbide layer was deposited by introducing oxygen at aflow rate of 160 sccm into the processing chamber, introducingoctamethylcyclotetrasiloxane at a flow rate of about 2900milligrams/minute (mgm) (which corresponds to about 226 sccm for OMCTS),introducing helium at a flow rate of about 1000 sccm, maintaining thechamber at a substrate temperature of about 350° C., maintaining achamber pressure of about 5 Torr, positioning a gas distributor at about450 mils from the substrate surface, and applying a RF power of about500 watts at 13.56 MHz and about 150 watts at 356 KHz.

Adhesion testing was performed on the test samples as follows. Betweenabout 120 μm and about 150 μm of epoxy material with known delaminationcharacteristics were deposited on the test samples. A layer of siliconwas deposited thereon. The test samples were then baked or cured for onehour at approximately 190° C. and then cleaved into 1 cm by 1 cm samplesand cooled to −170° C. with liquid nitrogen. The samples were thenobserved to determine delamination, which occurs at a weakest interlayerinterface at a given temperature. The shrinkage of the epoxy at a giventemperature correlates to the forces that are required to inducepeeling. From this observation, a determination of adhesion can becalculated. Adhesion (G_(C)) is based on the formula σ{squareroot}(h/2), with h being the epoxy thickness and being the residualstress. The measured adhesion G_(C) of an untreated or unmodified stackdescribed above was about 3 J-m² with a dielectric constant of about3.01 and delamination at the silicon carbonitride and silicon oxycarbideinterface.

In one sample, sample #1, a helium plasma treatment was performed on thesilicon carbonitride layer prior to deposition of the silicon oxycarbidelayer by providing helium to a processing chamber at a flow rate ofabout 1500 sccm, maintaining a chamber pressure of about 5 Torr,maintaining a substrate temperature of about 350° C., positioning a gasdistributor at about 450 mils from the substrate surface, and generatinga plasma by applying a RF power level of about 300 W at a high frequencyof about 13.56 MHz for a period of 15 seconds. The measured adhesionG_(C) of helium processed stack of sample #1 was about 3.8 J-m² with adielectric constant of about 3.03 and delamination did not occur at thesilicon carbonitride and silicon oxycarbide interface.

In another sample, sample #2, a helium plasma treatment and initiationlayer was performed on the silicon carbonitride layer prior todeposition of the silicon oxycarbide layer by the helium processdescribed in sample #1 and an initiation layer deposition by introducingoxygen at a flow rate of 500 sccm into the processing chamber,introducing octamethylcyclotetrasiloxane at a flow rate of about 500milligrams/minute (mgm) (which corresponds to about 39 sccm for OMCTS),introducing helium at a flow rate of about 4800 sccm, maintaining thechamber at a substrate temperature of about 350° C., maintaining achamber pressure of about 5 Torr, positioning a gas distributor at about350 mils from the substrate surface, and applying a RF power of about500 watts at 13.56 MHz and about 150 watts at 356 KHz. The measuredadhesion G_(C) of helium processed stack of sample #2 was about 5.5 J-m²with a dielectric constant of about 3.06 and delamination did not occurat the silicon carbonitride and silicon oxycarbide interface.

Layer Deposition:

Silicon Oxycarbide Layers

The silicon oxycarbide layer generally comprises silicon, carbon, andbetween about 15 atomic % or greater of oxygen. Oxygen doped siliconcarbide as described herein comprise less than about 15 atomic % ofoxygen. A preferred silicon oxycarbide layer comprises silicon-oxygenbonds and silicon-carbon bonds that contribute to low dielectricconstants and barrier properties. The carbon content of the depositedlayer is between about 5 atomic % and about 30 atomic % excludinghydrogen atoms, and is preferably between about 10 atomic % and about 20atomic % excluding hydrogen atoms. The deposited layers may contain C—Hor C—F bonds throughout to provide hydrophobic properties to the siliconoxycarbide layer. The silicon oxycarbide layer may also containhydrogen, nitrogen, or combinations thereof.

The silicon oxycarbide layers are deposited by oxidizing organosiliconcompounds, including both oxygen-containing organosilicon compounds andoxygen-containing organosilicon compounds, as described herein. In apreferred aspect of the invention, the silicon oxycarbide layer isdeposited by reacting an organosilicon compound comprising three or morealkyl groups with an oxidizing gas comprising ozone. The siliconoxycarbide layer may be deposited without an oxidizer if theorganosilicon compound includes oxygen. The preferred organosiliconcompounds include, for example:

-   -   trimethylsilane, (CH₃)₃—SiH    -   tetramethylsilane, (CH₃)₄—Si    -   1,1,3,3-tetramethyldisiloxane, (CH₃)₂—SiH—O—SiH—(CH₃)₂    -   hexamethyidisiloxane, (CH₃)₃—Si—O—Si—(CH₃₎ ₃    -   2,2-bis(1-methyldisiloxanyl)propane, (CH₃—SiH₂—O—SiH₂—)₂—C(CH₃)₂    -   1,3,5,7-tetramethylcyclotetrasiloxane, —(—SiHCH₃—O—)₄-(cyclic)    -   octamethylcyclotetrasiloxane, —(—Si(CH₃)₂—O—)₄-(cyclic)    -   1,3,5,7,9-pentamethylcyclopentasiloxane, —(—SiHCH_(3—O—))        ₅-(cyclic) and fluorinated derivatives thereof.

The organosilicon compounds are oxidized during deposition of thesilicon oxycarbide layer, preferably by reaction with oxygen (O₂), ozone(O₃), nitrous oxide (N₂O), carbon monoxide (CO), carbon dioxide (CO₂),water (H₂O), or combinations thereof, of which oxygen is preferred. Whenozone is used as an oxidizing gas, an ozone generator typically convertsabout 15 wt. % of the oxygen in a source gas to ozone, with theremainder typically being oxygen. However, the ozone concentration maybe increased or decreased based upon the amount of ozone desired and thetype of ozone generating equipment used. Organosilicon compounds thatcontain oxygen may be disassociated to provide the oxygen. Duringdeposition of the silicon oxycarbide layer, the substrate is maintainedat a temperature between about −20° C. and about 500° C., and preferablyis maintained at a temperature between about 170° C. and about 180° C.

For a plasma enhanced deposition of the silicon oxycarbide layer, theorganosilicon material is deposited using a power density rangingbetween about 0.003 W/cm² and about 6.4 W/cm² , which is a RF powerlevel of between about 1 W and about 2000 W for a 200 mm substrate.Preferably, the RF power level is between about 300 W and about 1700 W.The RF power is provided at a frequency between about 0.01 MHz and 300MHz. The RF power may be provided continuously or in short durationcycles wherein the power is on at the stated levels for cycles less thanabout 200 Hz, and the on cycles total between about 10% and about 50% ofthe total duty cycle. The deposition process of the low dielectricconstant layer is performed in a substrate processing system describedin more detail below. The silicon oxycarbide layer can be depositedcontinuously or with interruptions, such as changing chambers orproviding cooling time, to improve porosity.

Alternatively, a dual-frequency system may be applied to deposit thesilicon oxycarbide material. A dual-frequency source of mixed RF powerprovides a high frequency power in a range between about 10 MHz andabout 30 MHz, for example, about 13.56 MHz, as well as a low frequencypower in a range of between about 100 KHz and about 500 KHz, forexample, about 350 KHz. An example of a mixed frequency RF powerapplication may include a first RF power with a frequency in a range ofabout 10 MHz and about 30 MHz at a power in a range of about 200 wattsto about 1000 watts and at least a second RF power with a frequency in arange of between about 100 KHz and about 500 KHz as well as a power in arange of about 1 watt to about 200 watts. The ratio of the second RFpower to the total mixed frequency power is preferably less than about0.2 to 1.0.

In one aspect, a cyclic organosilicon compound and an aliphaticorganosilicon compound are reacted with an oxidizing gas in amountssufficient to deposit a low dielectric constant layer on a semiconductorsubstrate, wherein the cyclic organosilicon compound comprises at leastone silicon-carbon bond. The aliphatic organosilicon compound contains asilicon-hydrogen bond or a silicon-oxygen bond, preferably asilicon-hydrogen bond. For example, the cyclic organosilicon compoundmay be 1,3,5,7-tetramethylcyclotetrasiloxane oroctamethylcyclotetrasiloxane and the aliphatic organosilicon compoundmay be trimethylsilane or 1,1,3,3-tetramethyldisiloxane.

In another aspect, both the cyclic organosilicon compound and thealiphatic organosilicon compound contain a silicon-hydrogen bond. Forexample, 1,3,5,7-tetramethylcyclotetrasiloxane and trimethylsilane or1,1,3,3-tetramethyldisiloxane are blended and oxidized while applying RFpower.

In one embodiment of plasma enhanced deposition, oxygen or oxygencontaining compounds are dissociated to increase reactivity and toachieve desired oxidation of the deposited layer. RF power is coupled tothe deposition chamber to increase dissociation of the compounds. Thecompounds may also be dissociated in a microwave chamber prior toentering the deposition chamber.

Although deposition preferably occurs in a single deposition chamber,for example, the DxZ™ processing chamber or the Producer™ processingchamber, both of which are commercially available for Applied Materials,Inc., or Santa Clara, Calif., the silicon oxycarbide layer can bedeposited sequentially in two or more deposition chambers, e.g., topermit cooling of the layer during deposition. Additionally, the siliconoxycarbide and silicon carbide layers may be deposited in situ in thesame chamber and deposited subsequently by using selective precursorsand controlling the processing parameters and the composition ofprocessing gases. For example, both the silicon carbide and siliconoxycarbide layer may be deposited using trimethylsilane with ammoniabeing used in the silicon carbide deposition to form a nitrogen dopedsilicon carbide, and subsequently using ozone during deposition of thesilicon oxycarbide material.

Silicon Carbide Layers

The silicon carbide layer is deposited by reacting an organosiliconcompound to form a dielectric layer comprising carbon-silicon bonds anda dielectric constant less than about 4. The silicon carbide layer ispreferably an amorphous hydrogenated silicon carbide. The siliconcarbide layer may be deposited in a plasma of an inert gas, hydrogengas, or both. The silicon carbide dielectric layer may be a dopedsilicon carbide layer. The silicon carbide layer may be deposited as abarrier layer disposed adjacent a conductive material or dielectriclayer or may be an etch stop deposited between one or more dielectriclayers.

Examples of suitable organosilicon compounds used herein for siliconcarbide deposition preferably include the structure:

wherein R includes organic functional groups including alkyl, alkenyl,cyclohexenyl, and aryl groups, in addition to functional derivativesthereof. The organic precursors may have more than one R group attachedto the silicon atom, and the invention contemplates the use oforganosilicon precursors with or without Si—H bonds.

The organosilicon compounds include aliphatic organosilicon compounds,cyclic organosilicon compounds, or combinations thereof, having at leastone silicon-carbon bond, and optionally, the structure may includeoxygen. Cyclic organosilicon compounds typically have a ring comprisingthree or more silicon atoms. Aliphatic organosilicon compounds havelinear or branched structures comprising one or more silicon atoms andone or more carbon atoms. Commercially s available aliphaticorganosilicon compounds include organosilanes that do not contain oxygenbetween silicon atoms, and for oxygen doped silicon carbide layer,organosiloxanes that contain oxygen between two or more silicon atoms.Fluorinated derivatives of the organosilicon compounds described hereinmay also be used to deposit the silicon carbide and silicon oxycarbidelayers described herein.

Examples of suitable aliphatic and cyclic organosilicon compoundsinclude, for example, one or more of the following compounds:

-   -   Methylsilane, CH₃—SiH₃    -   Dimethylsilane, (CH₃)₂—SiH₂    -   Trimethylsilane (TMS), (CH₃)₃—SiH    -   Ethylsilane, CH₃—CH₂—SiH₃    -   Disilanomethane, SiH₃—CH₂—SiH₃    -   Bis(methylsilano)methane, CH₃—SiH₂—CH₂—SiH₂—CH₃    -   1,2-disilanoethane, SiH₃—CH₂—CH₂—SiH₃    -   1,2-bis(methylsilano)ethane, CH₃—SiH₂—CH₂—CH₂—SiH₂—CH₃    -   2,2-disilanopropane, SiH₃—C(CH₃)₂—SiH₃    -   1,3,5-trisilano-2,4,6trimethylene, —(—SiH₂CH₂—)₃ -(cyclic).

The above list is illustrative and should not be construed orinterpreted as limiting the scope of the invention.

Phenyl containing organosilicon compounds may also be used fordepositing the silicon carbide materials and generally include thestructure:

wherein R is a phenyl group. For example, suitable phenyl containingorganosilicon compounds generally includes the formulaSiH_(a)(CH₃)_(b)(C₆H₅)_(c), wherein a is 0 to 3, b is 0 to 3, and c is 1to 4, and a+b+c is equal to 4. Examples of suitable precursors derivedfrom this formula include diphenylsilane, dimethylphenylsilane,diphenylmethylsilane, phenylmethylsilane, and combinations thereof.Preferably used are phenyl containing organosilicon compounds with b is1 to 3 and c is 1 to 3. The most preferred organosilicon compounds fordeposition as barrier layer materials include organosilicon compoundshaving the formula SiH_(a)(CH₃)_(b)(C₆H₅)_(c), wherein a is 1 or 2, b is1 or 2, and c is 1 or 2. Examples of preferred precursors includedimethylphenylsilane and diphenylmethylsilane.

Generally, the organosilicon compounds are reacted in a plasmacomprising a relatively inert gas, such as nitrogen (N₂) and noblegases, such as helium or argon. The deposited silicon carbide layershave dielectric constants of about 5 or less, and the doped siliconcarbide layers may have dielectric constants of about 3 or less.

A preferred silicon carbide layer is deposited in one embodiment bysupplying trimethylsilane to a plasma processing chamber at a flow ratebetween about 10 milligrams/min (mgm) and about 5000 milligrams/min(mgm). Since conversion of milligram/minutes to standard cubiccentimeters per minute (sccm) may vary between organosilicon compounds,milligrams/min is preferably used for organosilicon compounds. An inertgas, such as helium, argon, or combinations thereof, is also supplied tothe chamber at a flow rate between about 50 sccm and about 5000 sccm.The chamber pressure is maintained between about 100 milliTorr and about15 Torr. The substrate surface temperature is maintained between about100° C. and about 450° C. during the deposition process. An exampleprocess for depositing a silicon carbide layer is disclosed in U.S. Pat.No. 6,537,733, issued on Mar. 25, 2003, which is incorporated byreference to the extent not inconsistent with the claims and disclosuredescribed herein.

The silicon carbide layer may also be a doped silicon carbide layercontaining oxygen, nitrogen, boron, phosphorus, or combinations thereof.Doped silicon carbide generally includes less than about 15 atomicpercent (atomic %) or less of one or more dopants. Dopants may be usedin the processing gases at a ratio of dopant to organosilicon compoundbetween about 1:5 or greater, such as between about 1:5 and about 1:100.

An oxygen source or a nitrogen source may be used during the reaction toform the oxygen doped and/or nitrogen doped silicon carbide layers.Examples of oxygen sources include oxidizing gases, such as oxygen,ozone, carbon monoxide, carbon dioxide, nitrous oxide, and oxygencontaining organosilicon precursor, or combinations thereof, such ascarbon monoxide and an oxygen containing organosilicon precursor. Oxygendoped silicon carbide generally includes less than about 15 atomicpercent (atomic %) of oxygen, preferably about 10 atomic % or less ofoxygen.

The oxygen containing organosilicon compounds include, for example:

-   -   Dimethyldimethoxysilane, (CH₃)₂—Si—(OCH₃)₂    -   1,3-dimethyldisiloxane, CH₃—SiH₂—O—SiH₂—CH₃    -   1,1,3,3-tetramethyldisiloxane (TMDSO), (CH₃)₂—SiH—O—SiH—(CH₃)₂    -   Hexamethyidisiloxane (HMDS), (CH₃)₃—Si—O—Si—(CH₃)₃    -   1,3-bis(silanomethylene)disiloxane, (SiH₃—CH₂—SiH₂—)₂—O    -   Bis(1-methyldisiloxanyl)methane, (CH₃—SiH₂—O—SiH₂—)₂—CH₂    -   2,2-bis(1-methyldisiloxanyl)propane, (CH₃—SiH₂—O—SiH₂—)₂—C(CH₃)₂    -   2,4,6,8-tetramethylcyclotetrasiloxane        (TMCTS)—(—SiHCH₃—O—)₄-(cyclic)    -   octamethylcyclotetrasiloxane (OMCTS), —(—Si(CH₃)₂—O—)₄-(cyclic)    -   2,4,6,8,10-pentamethylcyclopentasiloxane,        —(—SiHCH₃—O—)₅-(cyclic)    -   1,3,5,7-tetrasilano-2,6-dioxy-4,8-dimethylene,        —(—SiH₂—CH₂—SiH₂—O—)₂-(cyclic)    -   Hexamethylcyclotrisiloxane —(—Si(CH₃)₂—O—)₃-(cyclic)    -   1,3-dimethyldisiloxane, CH₃—SiH₂—O—SiH₂—CH₃    -   hexamethoxydisiloxane (HMDOS) (CH₃O)₃—Si—O—Si—(OCH₃)₃.        and fluorinated derivatives thereof.

Nitrogen doped silicon carbide may comprise up to 20 atomic % ofnitrogen and may be deposited by the addition of nitrogen containingcompounds including, for example, ammonia, nitrogen gas, a mixture ofnitrogen and hydrogen gas, and compounds having Si—N—Si bonding groups,such as silazane compounds. Examples of suitable silizane precursorsinclude aliphatic compounds, such as hexamethyidisilazane anddivinyltetramethyldisilizane, as well as cyclic compounds, such ashexamethylcyclotrisilazane.

For example, a doped silicon carbide layer can be deposited byintroducing an oxygen source and/or a nitrogen source, or other dopant,into the processing chamber at a flow rate between about 50 sccm andabout 10,000 sccm. For example, a nitrogen containing or nitrogen dopedsilicon carbide layer may be deposited by introducing a nitrogen source,such as ammonia, nitrogen, a mixture of nitrogen and hydrogen, orcombinations thereof, during deposition of the silicon carbide layer.

Phosphorus and/or boron doping of the low k silicon carbide layer may beperformed by introducing phosphine (PH₃) or borane (BH₃), or boranederivative thereof, such as diborane (B₂H₆), into the chamber during thedeposition process. It is believed that dopants may reduce thedielectric constant of the deposited silicon carbide material.Phosphorus and/or boron dopants may be introduced into the processingchamber at a flow rate between about 50 sccm and about 10,000 sccm.

Organic compounds, such as aliphatic hydrocarbon compounds may also beused in the processing gas to increase the carbon content of thedeposited silicon carbide materials. Suitable aliphatic hydrocarboncompounds include compounds having between one and about 20 adjacentcarbon atoms. The hydrocarbon compounds can include adjacent carbonatoms that are bonded by any combination of single, double, and triplebonds.

Example processes for depositing a nitrogen containing silicon carbidelayer is disclosed in U.S. patent application Ser. No. 09/627,667, filedon Jul. 28, 2000 Feb. 23, 2001, and U.S. Pat. No. 6,537,733, issued onMar. 25, 2003, which are incorporated by reference to the extent notinconsistent with the claims and disclosure described herein. An exampleprocess for depositing an oxygen containing silicon carbide layer isdisclosed in U.S. patent application Ser. No. 10/196,498, filed on Jul.15, 2002, which is incorporated by reference to the extent notinconsistent with the claims and disclosure described herein. An exampleprocess for depositing a boron and/or phosphorus silicon carbide layeris disclosed in U.S. patent application Ser. No. 10/342,079, filed onJan. 13, 2003, which is incorporated by reference to the extent notinconsistent with the claims and disclosure described herein.

Generally, the organosilicon compound, inert gas, and optional dopant,are introduced to the processing chamber via a gas distribution platespaced between about 200 millimeters (mm) and about 600 millimeters fromthe substrate on which the silicon carbide layer is being deposited.Power may be applied for a single or dual frequency RF power source. Forexample, power from a single 13.56 MHz RF power source is supplied tothe chamber 10 to form the plasma at a power density between about 0.003watts/cm and about 3.2 watts/cm, or a power level between about 1 wattand about 1000 watts for a 200 mm substrate. A power density betweenabout 0.9 watts/cm² and about 2.3 watts/cm², or a power level betweenabout 300 watts and about 700 watts for a 200 mm substrate, ispreferably supplied to the processing chamber to generate the plasma.

Alternatively, a dual-frequency system may be applied to deposit thesilicon carbide material. A dual-frequency source of mixed RF powerprovides a high frequency power in a range between about 10 MHz andabout 30 MHz, for example, about 13.56 MHz, as well as a low frequencypower in a range of between about 100 KHz and about 500 KHz, forexample, about 350 KHz. An example of a mixed frequency RF powerapplication may include a first RF power with a frequency in a range ofabout 10 MHz and about 30 MHz at a power in a range of about 200 wattsto about 1000 watts and at least a second RF power with a frequency in arange of between about 100 KHz and about 500 KHz as well as a power in arange of about 1 watt to about 200 watts. The ratio of the second RFpower to the total mixed frequency power is preferably less than about0.2 to 1.0.

Additionally, the ratio of the silicon source to the dopant in the gasmixture should have a range between about 1:1 and about 100:1. The aboveprocess parameters provide a deposition rate for the silicon carbidelayer in a range between about 100 Å/min and about 3000 Å/min whenimplemented on a 200 mm (millimeter) substrate in a deposition chamberavailable from Applied Materials, Inc., located in Santa Clara, Calif.

The embodiments described herein for depositing silicon carbide layersare provided to illustrate the invention, the particular embodimentshown should not be used to limit the scope of the invention. Theinvention also contemplates other processes and materials used todeposit silicon carbide layers.

While the foregoing is directed to preferred embodiments of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims which follow.

1. A method for processing a substrate, comprising: positioning thesubstrate in a processing chamber, wherein the substrate has a barrierlayer comprising at least silicon and carbon; introducing anorganosilicon compound and an oxidizing gas at a first ratio oforganosilicon compound to oxidizing gas into the processing chamber;generating a plasma of the oxidizing gas and the organosilicon compoundto form an initiation layer on the barrier layer; introducing theorganosilicon compound and the oxidizing gas at a second ratio oforganosilicon compound to oxidizing gas greater than the first ratiointo the processing chamber; and depositing a first dielectric layeradjacent the dielectric initiation layer, wherein the dielectric layercomprises silicon, oxygen, and carbon and has a dielectric constant ofabout 3 or less.
 2. The method of claim 1, wherein the barrier layerfurther comprises oxygen or nitrogen.
 3. The method of claim 1, whereinthe organosilicon compound is selected from the group oftrimethylsilane, 2,4,6,8-tetramethylcyclotetrasiloxane,octamethylcyclotetrasiloxane, and combinations thereof, and theoxidizing gas is selected from the group of oxygen, ozone, carbonmonoxide, carbon dioxide, nitrous oxide, and combinations thereof. 4.The method of claim 1, wherein the depositing the initiation layercomprises generating a plasma by a dual-frequency RF power source. 5.The method of claim 1, wherein the depositing the first dielectric layercomprises generating a plasma by a dual-frequency RF power source. 6.The method of claim 1, wherein the first ratio of the organosiliconcompound to the oxidizing gas comprises a ratio of about 1:1 and thesecond ratio of the organosilicon compound to the oxidizing gascomprises a ratio greater than or equal to about 10:1.
 7. The method ofclaim 1, further comprising introducing an inert gas with theorganosilicon compound and the oxidizing gas.
 8. The method of claim 1,further comprising exposing the barrier layer to a plasma of an inertgas, an oxidizing gas, or both, prior to introducing the oxidizing gasand the organosilicon compound.
 9. A method for processing a substrate,comprising: positioning the substrate in a processing chamber, whereinthe substrate has a barrier layer comprising silicon, nitrogen, andcarbon; introducing an inert gas into the processing chamber; generatinga first plasma from a single-frequency RF power source to modify asurface of the barrier layer; introducing an organosilicon compound andan oxidizing gas in a ratio of about 1:1 into the processing chamber;generating a second plasma from a dual-frequency RF power source to forman initiation layer on the barrier layer; introducing the organosiliconcompound and the oxidizing gas in a ratio of greater than or equal toabout 10:1 into the processing chamber; and depositing a firstdielectric layer adjacent the dielectric initiation layer, wherein thedielectric layer comprises silicon, oxygen, and carbon and has adielectric constant of about 3 or less.
 10. The method of claim 9,wherein the inert gas comprises helium, argon, or combinations thereof.11. The method of claim 9, wherein the organosilicon compound isselected from the group of trimethylsilane,2,4,6,8-tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, andcombinations thereof, and the oxidizing gas is selected from the groupof oxygen, ozone, carbon monoxide, carbon dioxide, nitrous oxide, andcombinations thereof.
 12. The method of claim 11, wherein an inert gasis introduced with the organosilicon compound.
 13. A method forprocessing a substrate, comprising: positioning the substrate in aprocessing chamber, wherein the substrate has a barrier layer comprisingat least silicon and carbon; introducing an oxidizing gas into theprocessing chamber; generating a plasma of the oxidizing gas andtreating a surface of the barrier layer; introducing an organosiliconcompound at a first flow rate; depositing an initiation layer on thebarrier layer from the oxidizing gas and the organosilicon compound;introducing the organosilicon compound at a second flow rate greaterthan the first flow rate; depositing a first dielectric layer adjacentthe dielectric initiation layer from the oxidizing gas and theorganosilicon compound, wherein the dielectric layer comprises silicon,oxygen, and carbon and has a dielectric constant of about 3 or less. 14.The method of claim 13, wherein the barrier layer further comprisesoxygen or nitrogen.
 15. The method of claim 13, wherein theorganosilicon compound is selected from the group of trimethylsilane,2,4,6,8-tetramethylcyclotetrasiloxane, octamethylcyclotetrasiloxane, andcombinations thereof, and the oxidizing gas is selected from the groupof oxygen, ozone, carbon monoxide, carbon dioxide, nitrous oxide, andcombinations thereof.
 16. The method of claim 13, wherein the generatingthe plasma of the oxidizing gas comprises generating a plasma by asingle-frequency RF power source and the depositing the initiation layercomprises generating a plasma by a dual-frequency RF power source. 17.The method of claim 13, wherein an inert gas is introduced with theorganosilicon compound.
 18. The method of claim 13, wherein thedepositing the initiation layer comprises the organosilicon compound andoxidizing gas present in a ratio of about 1:1.
 19. The method of claim13, wherein the depositing the first dielectric layer comprises theorganosilicon compound and oxidizing gas present in a ratio of greaterthan or equal to about 10:1.
 20. A method for processing a substrate,comprising: positioning the substrate in a processing chamber, whereinthe substrate has a barrier layer comprising at least silicon andcarbon; introducing an oxidizing gas into the processing chamber;generating a plasma of the oxidizing gas and forming an initiation layeron the barrier layer; introducing an organosilicon compound into theprocessing chamber; reacting the organosilicon compound and theoxidizing gas; and depositing a first dielectric layer adjacent theinitiation layer, wherein the dielectric layer comprises silicon,oxygen, and carbon and has a dielectric constant of about 3 or less.